As the present time is called a card age, cash cards, credit cards, and various other cards appear on the market. Most of them are magnetic recording cards and especially cards of the business card size, which are convenient in carrying, are very often used. However, since recording capacity is not so much assured in magnetic recording cards of such a size, it is the present state that they are only used to the extent of memorization of collation card, e.g., secret code, account number or registration number, etc. extremely restricted. In this respect, optical cards which optically record information have the merit that the information content recorded is far greater than that of conventional magnetic recording cards.
Such a system to record information onto an optical card to reproduce them therefrom is disclosed in, e.g., the Japanese Patent Application Laid-Open No. 137245/86 publication. In this system, the direction of a laser beam is controlled by two servo control mirrors, thus to carry out scanning of recording areas on the optical card. Further, a method is disclosed in the Japanese Patent Application Laid-Open No. 40325/84 publication to effect recording and reproducing while a vibrating laser beam in a direction vertical to the scanning direction of the optical card, and an actual mechanism for a scanning laser beam is disclosed in the Japanese Patent Application Laid-Open No. 214239/86 publication. In addition, a format for recording data onto an optical card with high efficiency is disclosed in the application No. JP86/00134 specification under the Patent Cooperation Treaty.
However, problems with the data recording and reproducing apparatus for an optical card conventionally known are as follows.
(1) For an optical disc, it is sufficient to carry out scanning by a laser beam by revolving the disc. In contrast, since it is necessary for an optical card to be scanned by a laser beam lengthwise and breadthwise, the mechanism of an optical system for scanning laser beam becomes complicated. In addition, the optical path of the laser beam becomes elongated, with the result that an optical aberration is likely to occur.
(2) The recording area on the surface of an optical card is likely to be subjected to adhesion of dust or scratched, with the result that reading errors may occur at the time of reproduction or playback.
(3) Since data is recorded in the order of .mu.m on the optical card, it is necessary to load the optical card at a correct position within the apparatus with the accuracy of .mu.m order. However, such an operation for loading the optical card is very troublesome in the conventional apparatus.
(4) In the optical card, a plurality of tracks are defined on the recording area to arrange pits along the tracks, thus to record information. For this reason, reproduction or playback is carried out while conducting a tracking control and a focusing control. However, since there is employed a system to conduct these controls while scanning the laser beam lengthwise and breadthwise in place of conducting them while revolving the disc as in the optical disc, the control system becomes extremely unstable.
(5) Since reading is conducted by scanning a laser beam lengthwise and breadthwise as described above, noise components are likely to be mixed into a read signal, so that reading in which noise components are eliminated is difficult.
(6) For a reading apparatus for an optical card, there is an apparatus of the type to conduct a reading of every bit trains using a line sensor. However, the apparatus of the type to scan using a laser beam to effect reading is not compatible with the apparatus using line sensor.